As is well known in the art of tablet type electrostatic digitizers, the signal that is generated by a signal source is coupled to the tablet by way of a capacitor whose components comprise the conductive pen tip, the tablet's upper insulator coating, and the tablet's lower conductive coating. Most of this capacitance effect is produced by a relatively small area of physical contact of the pen tip to the insulator coating. Generally speaking, the larger this contact area the larger will be the signal that is coupled to the tablet from the pen. With a rigid pen tip this capacitance is determined largely by the geometry of the pen tip, the geometry of the tablet, and the materials used in the pen tip and the tablet.
The art has provided graphics pens and the like whose tip or stylus is electrically conductive. U.S. Pat. No. 4,318,096 incorporated herein by reference is representative of this known feature of the art.
The general idea of providing a resilient contact pressure to a tablet is known. Reissue U.S. Pat. No. Re. 34,095 teaches a digitizer stylus having a tablet engaging pen refill of conventional pen refill construction. A pressure responsive transducer includes a movable plunger that is made of resilient material having a rounded surface that is deformed to increase the area of contact to a board as the stylus pressure increases.
While prior devices such as exemplified above are generally useful for their limited intended purposes, the need remains in the art for an electrostatic pen wherein the pen's tablet engaging tip is both electrically conductive and flexible, thus providing an increased capacitor-electrode contact area to a digitizing tablet as the tip is pressed down unto the tablet.